Thin layers used in semiconductor devices, such as gate insulation layers, dielectric layers in a capacitors, and dielectric layers in flash memory devices, may include high dielectric constant materials, or “high-k materials.” These high-k thin layers can sufficiently minimize current leakage between electrodes and channels in a gate structure, or between upper and lower electrodes in a capacitor with a relatively small equivalent oxide thickness (EOT). Further, thin layers including high-k materials can also improve the coupling ratio in flash memory devices. Examples of high-k materials include tantalum oxide (Ta2O5), yttrium oxide (Y2O3), hafnium oxide (HfO2), zirconium oxide (ZrO2), niobium oxide (Nb2O5), barium titanium oxide (BaTiO3), and strontium titanium oxide (SrTiO3).
Hafnium oxide is an example of a high-k material that has been used in semiconductor thin layers. For example, the use of hafnium oxide in semiconductor thin layers is discussed in U.S. Pat. No. 6,348,386. However, the dielectric constant of hafnium oxide is only about 20, so that the use of hafnium oxide may not be recommended for use in thin layers in the most recent semiconductor devices, wherein the layer material may have a dielectric constant over about 20.
As a result, zirconium oxide, which has a dielectric constant of about 55 and an EOT equivalent to hafnium oxide, may be used as a substitute for hafnium oxide in semiconductor thin layers. For example, methods of forming zirconium oxide layers are discussed in U.S. Patent Application Publication Nos. 2004-033698 and 2002-190294. However, zirconium oxide layers may have poor surface morphology, and thus, the electric field can become concentrated at certain areas of the surface of the zirconium oxide layer. These concentrations of electric field can cause current leakage from the surface of the zirconium oxide layer.
For these reasons, zirconium hafnium oxide may be used for thin layers in the latest semiconductor devices. The combination of zirconium and hafnium oxides may provide for a higher dielectric constant than a pure hafnium oxide layer, and may also provide for better surface morphology than a pure zirconium oxide layer.
Examples of semiconductor thin layers including zirconium hafnium oxide are discussed in Korean Patent Laid-Open Publication Nos. 2002-094933 and 2002-85794, which are assigned to Samsung Electronics Co., Ltd., and also in U.S. Patent Application Publication Nos. 2004-92073 and 2003-048666. For example, U.S. Patent Application Publication No. 2004-92073 discusses a method of forming a zirconium hafnium oxide layer by a chemical vapor deposition (CVD) process that uses a zirconium alkoxide as a zirconium precursor and a hafnium alkoxide as a hafnium precursor. As another example, Korean Patent Laid-Open Publication No. 2002-94933 discusses a method of forming a zirconium hafnium oxide layer by atomic layer deposition (ALD) using zirconium chloride (ZrCl4) and hafhium chloride (HfCl4).